I first learned of the new disk file metadata in December of 2021, when heated discussions about it occurred in a forum I was part of. It appears to me that the change was introduced in April of 2020 in this commit:
I wrote a little utility in Python to search my images for the presence of the new metadata, and add/edit/remove the metadata as desired:
I stopped thinking about the matter not long after that, I have not pulled fresh simh code from the repository in a while, and I do not know whether my utility code is still compatible with later versions of the pre-fork simh code. My usually-on VAX emulations are running on simh code from back in December.
I was surprised to see how this all escalated, since I've been living under a virtual rock for a while. I assume that I'll be switching to the new open-simh fork next time simh activities move to my front burner, because the license changes which apparently prompted the fork look rather distasteful to me. I'm interested in seeing if the metadata stuff gets any changes in the future in open-simh.